U.S. patent application number 14/185429 was filed with the patent office on 2014-08-28 for coated overhead conductors and methods.
This patent application is currently assigned to GENERAL CABLETECHNOLOGIES CORPORATION. The applicant listed for this patent is General Cable Technologies Corporation. Invention is credited to Cody R. DAVIS, Vijay MHETAR, Sathish K. RANGANATHAN, Srinivas SIRIPURAPU.
Application Number | 20140238867 14/185429 |
Document ID | / |
Family ID | 51387050 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140238867 |
Kind Code |
A1 |
RANGANATHAN; Sathish K. ; et
al. |
August 28, 2014 |
COATED OVERHEAD CONDUCTORS AND METHODS
Abstract
A coated overhead conductor having an assembly including one or
more conductive wires, such that the assembly includes an outer
surface coated with an electrochemical deposition coating forming
an outer layer, wherein the electrochemical deposition coating
includes a first metal oxide, such that the first metal oxide is
not aluminum oxide. Methods for making the overhead conductor are
also provided.
Inventors: |
RANGANATHAN; Sathish K.;
(Plainfield, IN) ; MHETAR; Vijay; (US) ;
DAVIS; Cody R.; (Maineville, OH) ; SIRIPURAPU;
Srinivas; (Carmel, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Cable Technologies Corporation |
Highland Heights |
KY |
US |
|
|
Assignee: |
GENERAL CABLETECHNOLOGIES
CORPORATION
Highland Heights
KY
|
Family ID: |
51387050 |
Appl. No.: |
14/185429 |
Filed: |
February 20, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61769492 |
Feb 26, 2013 |
|
|
|
Current U.S.
Class: |
205/250 ;
205/108; 205/159; 205/162; 205/320; 205/323; 205/333; 205/95 |
Current CPC
Class: |
C25D 11/02 20130101;
C25D 7/0607 20130101; C25D 11/024 20130101; C25D 11/026 20130101;
H01B 7/421 20130101; H01B 3/105 20130101; C25D 11/022 20130101;
H01B 5/002 20130101; C25D 11/08 20130101; C25D 11/06 20130101 |
Class at
Publication: |
205/250 ;
205/333; 205/95; 205/323; 205/320; 205/159; 205/162; 205/108 |
International
Class: |
H01B 7/42 20060101
H01B007/42; C25D 7/06 20060101 C25D007/06 |
Claims
1. A coated overhead conductor comprising an assembly including one
or more conductive wires, wherein the assembly comprises an outer
surface coated with an electrochemical deposition coating forming
an outer layer, wherein the electrochemical deposition coating
comprises a first metal oxide, wherein the first metal oxide is not
aluminum oxide.
2. The coated overhead conductor of claim 1, wherein the first
metal oxide comprises titanium oxide, zirconium oxide, zinc oxide,
niobium oxide, vanadium oxide, molybdenum oxide, copper oxide,
nickel oxide, magnesium oxide, beryllium oxide, cerium oxide, boron
oxide, gallium oxide, hafnium oxide, tin oxide, iron oxide, yttrium
oxide or combinations thereof.
3. The coated overhead conductor of claim 1, wherein the one or
more conductive wires are formed of aluminum or aluminum alloy.
4. The coated overhead conductor of claim 3, wherein the outer
layer is further formed of a second metal oxide, wherein the second
metal oxide is aluminum oxide.
5. The coated overhead conductor of claim 1, wherein the one or
more conductive wires are formed of copper or copper alloy.
6. The coated overhead conductor of claim 2, wherein the first
metal oxide comprises titanium oxide, zirconium oxide or
combinations thereof.
7. The coated overhead conductor of claim 1 having a lower
operating temperature compared to the operating temperature of an
uncoated overhead conductor at similar operating conditions.
8. The coated overhead conductor of claim 1, wherein the
electrochemical deposition coating is non-white.
9. The coated overhead conductor of claim 1, wherein the outer
layer has a thickness of about 1 micron or more.
10. The coated overhead conductor of claim 1, wherein the outer
layer has a thickness of about 5 microns to about 25 microns.
11. The coated overhead conductor of claim 1, wherein the outer
layer has a thickness variation of about 3 microns or less.
12. The coated overhead conductor of claim 1 having an operating
temperature reduced by at least 5.degree. C. when compared to the
operating temperature of an uncoated overhead conductor at similar
operating conditions.
13. The coated overhead conductor of claim 1 having an operating
temperature reduced by at least 10.degree. C. when compared to the
operating temperature of an uncoated overhead conductor, when the
operating temperatures measured are above 100.degree. C. and at
similar operating conditions.
14. The coated overhead conductor of claim 1 having reduced power
transmission loss when compared to an uncoated overhead conductor
at similar operating conditions.
15. The coated overhead conductor of claim 1 having increased
current carrying capacity when compared to an uncoated overhead
conductor at similar operating conditions.
16. The coated overhead conductor of claim 3, wherein the one or
more conductive wires are formed from an aluminum alloy selected
from the group consisting of 1350 alloy aluminum, 6000-series alloy
aluminum, aluminum-zirconium alloy, and combinations thereof.
17. The coated overhead conductor of claim 1, wherein at least some
of the one or more conductive wires have trapezoidal
cross-sections.
18. The coated overhead conductor of claim 1, wherein the one or
more conductive wires surround a core comprised of steel, carbon
fiber composite, glass fiber composite, carbon nanotube composite,
or aluminum alloy.
19. The coated overhead conductor of claim 1, wherein each of the
conductive wires is individually coated with the electrochemical
deposition coating.
20. The coated overhead conductor of claim 1, wherein a portion of
each of the conductive wires is coated with the electrochemical
deposition coating.
21. The coated overhead conductor of claim 1, wherein the
electrochemical deposition coating is electrically
non-conductive.
22. A method for making a coated overhead conductor, the method
comprising: a. providing a bare conductor; and b. performing
electrochemical deposition of a first metal oxide on an outer
surface of the bare conductor to form an outer layer on the bare
conductor, the outer layer comprising an electrochemical deposition
coating, wherein the first metal oxide is not aluminum oxide.
23. The method of claim 22, wherein the electrochemical deposition
coating is non-white.
24. The method of claim 22, wherein the first metal oxide is
titanium oxide, zirconium oxide, zinc oxide, niobium oxide,
vanadium oxide, molybdenum oxide, copper oxide, brass oxide, nickel
oxide, magnesium oxide, beryllium oxide, cerium oxide, boron oxide,
gallium oxide, hafnium oxide, tin oxide, iron oxide, yttrium oxide,
or combinations thereof.
25. The method of claim 22, wherein the outer layer has a thickness
of about 1 micron to about 25 microns.
26. The method of claim 22, wherein the outer layer has a thickness
variation of about 3 microns or less.
27. The method of claim 22, wherein the coated overhead conductor
has an operating temperature reduced by at least 5.degree. C.
compared to the operating temperature of an uncoated overhead
conductor at similar operating conditions.
28. The method of claim 22, wherein the coated overhead conductor
has an operating temperature reduced by at least 10.degree. C.
compared to the operating temperature of an uncoated overhead
conductor, when the operating temperatures is above 100.degree. C.
at similar operating conditions.
29. The method of claim 22, wherein the coated overhead conductor
has reduced power transmission loss when compared to an uncoated
overhead conductor at similar operating conditions.
30. The method of claim 22, wherein the coated overhead conductor
has increased current carrying capacity when compared to an
uncoated overhead conductor at similar operating conditions.
31. The method of claim 22, wherein the bare conductor comprises a
plurality of conductor wires made from one or more of copper,
copper alloy, aluminum, or aluminum alloy.
32. The method of claim 31, wherein the plurality of conductive
wires are formed from an aluminum alloy comprising 1350 alloy
aluminum, 6000-series alloy aluminum, or aluminum-zirconium
alloy.
33. The method of claim 22, wherein the bare conductor comprises a
plurality of conductive wires, wherein at least some of the
plurality of conductive wires have a trapezoidal cross-section.
34. The method of claim 22, wherein the bare conductor comprises a
plurality of conductive wires stranded around a core, and wherein
the core is comprises steel, carbon fiber composite, glass fiber
composite, carbon nanotube composite, or aluminum alloy.
35. The method of claim 22, wherein the bare conductor is formed of
a plurality of conductive wires, and wherein the electrochemical
deposition coats only an outer surface of the bare conductor.
36. The method of claim 22, wherein the bare conductor comprises a
plurality of conductive wires, and wherein the electrochemical
deposition coats each of the conductive wires.
37. The method of claim 22, wherein the electrochemical deposition
coats only a portion of the bare conductor.
38. The method of claim 22, wherein the electrochemical deposition
coating is electrically non-conductive.
39. The method of claim 22 being continuous, semi-continuous, or
batch.
40. The method of claim 22, wherein the performance of the
electrochemical deposition comprises: i. providing an aqueous
solution containing at least one of water-soluble complex metal
fluorides, water-dispersible complex metal fluorides, water-soluble
complex metal oxyfluorides, and water-dispersible metal
oxyfluorides; ii. providing a cathode in contact with said aqueous
solution; iii. placing the bare conductor in the aqueous solution
as an anode; iv. passing a current between the anode and the
cathode through the aqueous solution to form the electrochemical
deposition coating on the outer surface of the bare conductor; and
v. removing the coated overhead conductor from the aqueous
solution.
41. The method of claim 40, wherein the current is pulsed.
42. The method of claim 40, wherein the current is from about 10
amps/square foot to about 400 amps/square foot.
43. The method of claim 40, wherein the metal is titanium or
zirconium.
44. The method of claim 22, wherein the metal oxide is titanium
oxide or zirconium oxide.
45. A coated overhead conductor comprising an assembly including
one or more conductive wires, wherein the one or more conductive
wires are formed of aluminum or aluminum alloy, wherein the
assembly comprises an outer surface coated with an electrochemical
deposition coating forming an outer layer, the electrochemical
deposition coating comprises titanium oxide, zirconium oxide or
combinations thereof, and the outer layer has a thickness from
about 5 microns to about 25 microns.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority of U.S. provisional
application Ser. No. 61/769,492, filed Feb. 26, 2013, and hereby
incorporates the same application herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present disclosure generally relates to a coated
overhead conductor which better radiates heat away, thereby
reducing operating temperature.
BACKGROUND
[0003] As the need for electricity continues to grow, the need for
higher capacity transmission and distribution lines grows as well.
The amount of power a transmission line can deliver is dependent on
the current-carrying capacity (ampacity) of the line. For a given
size of the conductor, the ampacity of the line is limited by the
maximum safe operating temperature of the bare conductor that
carries the current. Exceeding this temperature can result in
damage to the conductor or the accessories of the line. Moreover,
the conductor gets heated by Ohmic losses and solar heat and cooled
by conduction, convection and radiation. The amount of heat
generated due to Ohmic losses depends on current (I) passing
through the conductor and its electrical resistance (R) by the
relationship--Ohmic losses=I.sup.2R. Electrical resistance (R)
itself depends on temperature. Higher current and temperature lead
to higher electrical resistance, which, in turn, leads to more
electrical losses in the conductor.
SUMMARY
[0004] In accordance with one embodiment, a coated overhead
conductor includes an assembly including one or more conductive
wires. The assembly also includes an outer surface coated with an
electrochemical deposition coating forming an outer layer. The
electrochemical deposition coating includes a first metal oxide.
The first metal oxide is not aluminum oxide.
[0005] In accordance with another embodiment, a method of making a
coated overhead conductor includes providing a bare conductor and
performing electrochemical deposition of a first metal oxide on an
outer surface of the bare conductor to form an outer layer on the
bare conductor. The outer layer includes an electrochemical
deposition coating. The first metal oxide is not aluminum
oxide.
[0006] In accordance with yet another embodiment, a coated overhead
conductor includes an assembly including one or more conductive
wires. The one or more conductive wires are formed of aluminum or
aluminum alloy. The assembly includes an outer surface coated with
an electrochemical deposition coating forming an outer layer. The
electrochemical deposition coating includes titanium oxide,
zirconium oxide or combinations thereof. The outer layer has a
thickness from about 5 microns to about 25 microns.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various embodiments will become better understood with
regard to the following description, appended claims and
accompanying drawings wherein:
[0008] FIG. 1 is a cross-sectional view of an overhead conductor in
accordance with one embodiment.
[0009] FIG. 2 is a cross-sectional view of an overhead conductor in
accordance with another embodiment.
[0010] FIG. 3 is a cross-sectional view of an overhead conductor in
accordance with yet another embodiment.
[0011] FIG. 4 is a cross-sectional view of an overhead conductor in
accordance with still another embodiment.
[0012] FIG. 5 is a test setup to measure the temperature of coated
and uncoated energized aluminum substrates, in accordance with an
embodiment.
DETAILED DESCRIPTION
[0013] Selected embodiments are hereinafter described in detail in
connection with the views and examples of FIGS. 1-5.
[0014] Metal oxide coated overhead conductors, when tested in under
similar current and ambient conditions, can have a reduced
operating temperature by at least 5.degree. C. compared to the
temperature of the same conductor without the surface
modification.
[0015] Accordingly, it can be desirable to provide a modified
overhead conductor that operates at significantly lower
temperatures compared to an unmodified overhead conductor that
operates under the same operating conditions, such as current and
ambient conditions. Such a modified overhead conductor can have a
coating of metal oxide other than aluminum oxide, such that when
tested under similar current and ambient conditions, has a reduced
operating temperature by at least 5.degree. C. compared to the
operating temperature of the same conductor without the coating. At
higher operating temperatures, e.g. above 100.degree. C., a coated
conductor can have a reduction of at least 10.degree. C. when
compared to an uncoated conductor when tested under similar current
and ambient conditions (e.g., operating conditions).
[0016] Overhead conductors can be coated using a variety of
techniques; however, one advantageous method includes coating the
overhead conductor via electrochemical deposition with a metal
oxide on the surface of the overhead conductor. The method can
contain the steps of: [0017] a) Pretreatment: cleaning and
preparing the surface of the overhead conductor; [0018] b) Coating:
coating the surface of overhead conductor with metal oxide coating
using electrochemical deposition; [0019] c) Rinsing (optional); and
[0020] d) Drying: drying the coated overhead conductor in air or in
an oven.
[0021] Suitable pre-treatment for a surface of an overhead
conductor can include hot water cleaning, ultrasonic, de-glaring,
sandblasting, chemicals (like alkaline or acidic), and others or a
combination of the above methods. The pre-treatment process can be
used to remove dirt, dust, and oil for preparing the surface of the
overhead conductor for electrochemical deposition.
[0022] The overhead conductor can be made of conductive wires of
metal or metal alloy. Examples include copper and aluminum and the
respective alloys. Aluminum and its alloys are advantageous for an
overhead conductor due to their lighter weight.
[0023] Electrochemical deposition of a metal oxide is one method
for coating the surface of an overhead conductor. Electrochemical
coating compositions using an electrochemical deposition process
can include, for example, those found in U.S. Pat. Nos. 8,361,630,
7,820,300, 6,797,147 and 6,916,414; U.S. Patent Application
Publication Nos. 2010/0252241, 2008/0210567, 2007/0148479; and WO
2006/136335A1; which are each incorporated herein by reference in
their entirety.
[0024] One method for forming a metal oxide coated aluminum
overhead conductor can include the steps of: providing an anodizing
solution comprising an aqueous water soluble complex of fluoride
and/or oxyfluoride of a metal ion selected from one or more of
titanium, zirconium, zinc, vanadium, hafnium, tin, germanium,
niobium, nickel, magnesium, berrilium, cerium, gallium, iron,
yttrium and boron, placing a cathode in the anodizing solution,
placing the surface of the overhead conductor as an anode in the
anodizing solution, applying a current across the cathode and the
anode through the anodizing solution for a period of time effective
to coat the aluminum surface, at least partially, with a metal
oxide on the surface of the surface of the conductor to form a
coating. Such coatings having a metal oxide can include a ceramic
coating.
[0025] In one embodiment, electrochemical deposition of the coating
includes maintaining an anodizing solution at a temperature between
0.degree. C. and 90.degree. C.; immersing at least a portion of the
surface of the overhead conductor in the anodizing solution; and
applying a voltage to the overhead conductor. The anodizing
solution can be contained within a bath or a tank.
[0026] The current passed through a cathode, anode and anodizing
solution can include pulsed direct current, non-pulsed direct
current and/or alternating current. When using pulsed current, an
average voltage potential can generally be not in excess of 600
volts. When using direct current (DC), suitable range is 10 to 400
Amps/square foot and 150 to 600 volts. In a certain embodiment, the
current is pulsed with an average voltage of the pulsed direct
current is in a range of 150 to 600 volts; in a certain embodiment
in a range of 250 to 500 volts; in a certain embodiment in a range
of 450 volts. Non-pulsed direct current is desirably used in the
range of 200-600 volts.
[0027] A number of different types of anodizing solutions can be
used. For example, a wide variety of water-soluble or
water-dispersible anionic species containing metal, metalloid,
and/or non-metal elements are suitable for use as components of the
anodizing solution. Representative elements can include, for
example, titanium, zirconium, zinc, vanadium, hafnium, tin,
germanium, niobium, nickel, magnesium, berrilium, cerium, gallium,
iron, yttrium and boron and the like (including combinations of
such elements). In certain embodiments, components of the anodizing
solution are titanium and/or zirconium.
[0028] In one embodiment, the anodizing solution can contain water
and at least one complex fluoride or oxyfluoride of an element
selected from the group consisting of titanium, zirconium, zinc,
vanadium, hafnium, tin, germanium, niobium, nickel, magnesium,
berrilium, cerium, gallium, iron, yttrium and boron. In certain
embodiments such elements are titanium and/or zirconium. In certain
embodiments, the coating can further contain IR reflective
pigments.
[0029] In another embodiment, a method for making an overhead
conductor can include providing of a metal oxide coating. The
method can include providing an anodizing solution containing
water, a phosphorus containing acid and/or salt, and one or more
additional components selected from the group consisting of:
water-soluble complex fluorides, water-soluble complex
oxyfluorides, water-dispersible complex fluorides, and
water-dispersible complex oxyfluorides of elements selected from
the group consisting of titanium and zirconium, placing a cathode
in the anodizing solution, placing the overhead conductor having a
surface of an aluminum or aluminum alloy as an anode in the
anodizing solution, passing a pulsed current across the cathode and
the anode through the anodizing solution for a period of time
effective to form a titanium oxide or zirconium oxide coating on at
least a surface of the overhead conductor.
[0030] Electrochemical deposition of a metal oxide coating can be
achieved either directly on the finished conductor or coating
individual conductive wires separately before stranding the coated
individual wires to make the overhead conductor. In certain
embodiments, it is possible to have all of the wires of the
conductor surface coated, or more economically, via another
embodiment, only having the outer most wires of the conductor
surface coated. In another embodiment, the electrochemical
deposition coating can be applied only to the outer surface of the
overhead conductor. Here, the conductor itself is stranded and made
into final form before electrochemical deposition. Electrochemical
deposition can be done by batch process, semi-continuous process,
continuous process, or combinations of these processes.
[0031] FIGS. 1, 2, 3, and 4 illustrate various bare overhead
conductors according to various embodiments incorporating a coated
surface.
[0032] As seen in FIG. 1, an overhead conductor 100 generally
includes a core 110 of one or more wires, round conductive wires
130 around the core 110, and a coating layer 120. The core 110 can
be formed from any of a variety of suitable materials including,
for example, steel, invar steel, carbon fiber composite, or any
other material providing strength to the conductor 100. The
conductive wires 130 can be made from a conductive material, such
as copper, copper alloy, aluminum, or aluminum alloy. Such aluminum
alloys can include aluminum types 1350, 6000 series alloy aluminum,
or aluminum-zirconium alloy, for example.
[0033] As seen in FIG. 2, an overhead conductor 200 can generally
include round conductive wires 210 and a coating layer 220. Again,
in certain embodiments, the conductive wires 210 can be made from a
conductive material, such as copper, copper alloy, aluminum, or
aluminum alloy. Such aluminum alloys can include aluminum types
1350, 6000 series alloy aluminum, or aluminum-zirconium alloy, for
example.
[0034] As seen in FIG. 3, an overhead conductor 300 can generally
include a core 310 of one or more wires, trapezoidal shaped
conductive wires 330 around the core 310, and a coating layer 320.
The core 310 can be formed from any of a variety of suitable
materials including, for example, steel (e.g. invar steel),
aluminum alloy (e.g. 600 series aluminum alloy), carbon fiber
composite, glass fiber composite, carbon nanotube composite, or any
other material providing strength to the overhead conductor 300.
Again, in certain embodiments, the conductive wires 330 can be made
from a conductive material, such as copper, copper alloy, aluminum,
or aluminum alloy. Such aluminum alloys can include aluminum types
1350, 6000 series alloy aluminum, or aluminum-zirconium alloy, for
example.
[0035] As seen in FIG. 4, an overhead conductor 400 is generally
shown to include trapezoidal-shaped conductive wires 420 and a
coating layer 410. Again, in certain embodiments, the conductive
wires 420 can be made from a conductive material, such as copper,
copper alloy, aluminum, or aluminum alloy. Such aluminum alloys can
include aluminum types 1350, 6000 series alloy aluminum, or
aluminum-zirconium alloy, for example.
[0036] Composite core conductors can beneficially provide lower sag
at higher operating temperatures and higher strength to weight
ratio. Reduced conductor operating temperatures due to surface
modification can further lower sag of the conductors and lower
degradation of polymer resin in the composite core.
[0037] The surface modification described herein can also be
applied in association with conductor accessories and overhead
conductor electrical transmission related products and parts, for
the purpose of achieving temperature reduction. Examples include
deadends/termination products, splices/joints products, suspension
and support products, motion control/vibration products (also
called dampers), guying products, wildlife protection and deterrent
products, conductor and compression fitting repair parts,
substation products, clamps and other transmission and distribution
accessories. Such products are commercially available from a number
of manufacturers such as Preformed Line Products (PLP), Cleveland,
Ohio, and AFL, Duncan, S.C.
[0038] The electrochemical deposition coating can have a desired
thickness on the surface of the overhead conductor. In certain
embodiments, this thickness can be from about 1 micron to about 100
microns; in certain embodiments from about 1 micron to about 25
microns; and in certain embodiments, from about 5 microns to about
20 microns. The thickness of the coating can be surprisingly even
along the conductor. For example, in certain embodiments, the
thickness can have a variation of about 3 microns or less; in
certain embodiments, of about 2 microns or less; and in certain
embodiments, of about 1 micron or less. Such electrochemical
deposition coatings as described herein can be non-white in color.
In certain embodiments, the color of the electrochemical deposition
coatings can range in color from blue-grey and light grey to
charcoal grey depending upon the coating thickness and relative
amounts of metal oxides, such as titanium oxide and/or zinc oxide.
In certain embodiments, such coatings can also be electrically
non-conductive. As used herein, "electrically non-conductive" means
volume resistivity greater than or equal to 1.times.10.sup.4
ohm-cm.
[0039] Without further description, it is believed that one of
ordinary skill in the art can, using the preceding description and
the following illustrative examples, make and utilize the coatings
and overhead conductors as described herein and practice the
claimed methods. The following examples are given to further
illustrate the claimed invention. It should be understood that the
claimed invention is not to be limited to the specific conditions
or details described in the cited examples.
Experimental Set-Up to Measure Effect of Coating on Operating
Temperature of Conductor
[0040] An experimental set-up to measure the effectiveness of an
electrochemical deposition coating to reduce operating temperature
of a conductor is prepared as described below. A current is applied
through coated and uncoated samples. The coated sample can be a
metal oxide coated aluminum or aluminum alloy substrate. The
uncoated sample can be a similar aluminum or aluminum alloy
substrate, but uncoated. The test apparatus is shown in FIG. 5 and
mainly includes a 60 Hz AC current source, a true RMS clamp-on
current meter, a temperature datalog recording device, and a timer.
Testing was conducted within a 68'' wide.times.33'' deep windowed
safety enclosure to control air movement around the sample. An
exhaust hood was located 64'' above the test apparatus for
ventilation.
[0041] The sample to be tested was connected in series with the AC
current source through a relay contact controlled by the timer. The
timer was used to control the time duration of the test. The 60 Hz
AC current flowing through the sample was monitored by the true RMS
clamp-on current meter. A thermocouple was used to measure the
surface temperature of the sample. Using a spring clamp, the tip of
the thermocouple was kept firmly in contact with the center surface
of the sample. The thermocouple was monitored by the temperature
datalog recording device to provide a continuous record of
temperature.
[0042] Both uncoated and coated substrate samples were tested for
temperature rise on this experimental set-up under identical
conditions. The current was set at a desired level and was
monitored during the test to ensure that a constant current was
flowing through the samples. The timer was set at a desired value;
and the temperature datalog recording device was set to record
temperature at a recording interval of one reading per second.
[0043] The metal component for the uncoated and coated samples was
from the same source material and lot of Aluminum 1350. The
finished dimensions of the uncoated sample was
12.0''(L).times.0.50''(W).times.0.027''(T). The finished dimensions
of the coated sample was
12.0''(L).times.0.50''(W).times.0.028''(T). The increase in
thickness was due to the thickness of the applied coating.
[0044] The uncoated sample was firmly placed into the test set-up
and the thermocouple secured to the center portion of the sample.
Once this was completed, the current source was switched on and was
adjusted to the required ampacity load level. Once this was
achieved the power was switched off. For the test itself, once the
timer and the temperature datalog recording device were all
properly set, the timer was turned on to activate the current
source starting the test. The desired current flowed through the
sample and the temperature started rising. The surface temperature
change of the sample was automatically recorded by the temperature
datalog recording device. Once the testing period was completed,
the timer automatically shut down the current source ending the
test.
[0045] Once the uncoated sample was tested, it was removed from the
set-up and replaced by the coated sample. The testing resumed
making no adjustments to the AC current source. The same current
level was passed through the uncoated and coated samples.
[0046] The temperature test data was then accessed from the
temperature datalog recording device and analyzed using a computer.
Comparing the results from the uncoated sample test with that from
the coated test was used to determine the comparative emissivity
effectiveness of the coating material.
Methodology to Measure Flexibility and Thermal Stability of
Coating
[0047] To study thermal stability of an electrochemical deposition
coating, coated samples were places in air circulation oven at a
temperature of 325.degree. C. for a period of 1 day and 7 days.
After the thermal aging was complete, the samples were placed at
room temperature for a period of 24 hrs. The samples were then bent
on different cylindrical mandrels sized from larger diameter to
smaller diameter and the coatings were observed for any visible
cracks at each of the mandrel sizes. Results were compared with the
flexibility of the coating prior to thermal aging.
EXAMPLES
Comparative Example 1
[0048] Uncoated strips of aluminum (ASTM grade 1350; Dimensions:
12.0''(L).times.0.50''(W).times.0.028''(T)) were tested for
operating temperature as per the test method described above. The
test set up is illustrated in FIG. 5.
Inventive Example 1
[0049] The same strips of aluminum described in Comparative Example
1 were coated with an electrochemical deposition coating of
titanium oxide (commercially available as Alodine EC2 from Henkel
Corporation). The sample dimensions prior to coating were
12.0''(L).times.0.50''(W).times.0.028''(T). The thickness of the
coating was 12-15 microns. The sample was then tested for reduction
in operating temperature by the test method described above. The
titanium oxide coated sample was found to demonstrate significantly
lower operating temperature compared to the uncoated sample
(Comparative Example 1), as summarized in Table 1 below.
TABLE-US-00001 TABLE 1 Operating temperature reduction data for
coated & uncoated sample Comparative Inventive Example 1
Example 1 Substrate Aluminum 1350 Aluminum 1350 Coating None
Titanium Oxide Conductor Temperature at 95 Amp 127 103 current
(.degree. C.)
Comparative Example 2
[0050] The same strips of aluminum described in Comparative Example
1 were anodized. The anodized layer thickness was 8-10 microns. The
flexibility of the anodized coating was tested by performing the
mandrel bend test as described above. The flexibility test was also
conducted after thermal aging at 325.degree. C. for 1 day and 7
days.
Comparative Example 3
[0051] The same strips of aluminum described in Comparative Example
1 were coated with a coating containing 40% sodium silicate
solution in water (75% by weight) and zinc oxide (25% by weight) by
brush application. The coating thickness was about 20 microns.
Flexibility of the coating was tested by performing the mandrel
bend test as described above. The flexibility test was also
conducted after thermal aging at 325.degree. C. for 1 day and 7
days.
[0052] The flexibility test data is summarized in Table 2 below.
The sample with the electrochemically deposited titanium oxide
coating showed significantly better flexibility compared to each of
the anodized coating and the sodium silicate with ZnO brush
coating. Moreover there was no change in the flexibility of the
titanium oxide coating with thermal aging at 325.degree. C. for 1
and 7 days.
TABLE-US-00002 TABLE 2 Flexibility and thermal stability data for
differently coated samples Comparative Comparative Inventive
Example 2 Example 3 Example 1 Substrate Aluminum 1350 Aluminum 1350
Aluminum 1350 Coating Anodized Sodium silicate + Titanium Oxide
Zinc Oxide Application of Anodized Brushed Electrochemical Coating
Deposition Before ageing 8'' mandrel 4'' mandrel 1'' mandrel
(Initial) Cracks observed Cracks Pass - no cracks observed observed
After heat 8'' mandrel 4'' mandrel 1'' mandrel ageing at Cracks
observed Cracks Pass - no cracks 325.degree. C. for observed
observed 1 day After heat 8'' mandrel 4'' mandrel 1'' mandrel
ageing at Cracks observed Cracks Pass - no cracks 325.degree. C.
for observed observed 7 days
[0053] While particular embodiments have been chosen to illustrate
the claimed invention, it will be understood by those skilled in
the art that various changes and modifications can be made therein
without departing from the scope of the claimed invention as
defined in the appended claims.
* * * * *